• Dr Andy Raffles

Developmental Dysplasia of the Hip (also called Congenital Hip Dislocation or Hip Dysplasia)

Developmental dysplasia of the hip (DDH) is a condition where the ‘ball and socket’ joint of the hip does not properly form in babies and young children. The hip joint attaches the thigh bone (femur) to the pelvis. The top of the femur (femoral head) is rounded, like a ball, and sits inside the cup-shaped hip socket. In DDH, the socket of the hip is too shallow, and the femoral head is not held tightly in place, so the hip joint is loose. In severe cases, the femur can come out of the socket (dislocate).


DDH may affect one or both hips, but for some reason, it is more common in the left hip. It's also more common in girls and firstborn children. There also seems to be an association with having ancestry from the Mediterranean area. The initial instability is also thought to be caused by joint laxity or looseness due to the effects of maternal hormones, genetically determined laxity, and occasionally related to the position in the womb. The genetic link is very much the most powerful predictor, so if anyone in your family has had the condition you should inform the healthcare professionals who look after you.


About 1 or 2 in every 1,000 babies have DDH that needs to be treated. Without treatment, DDH may lead to problems later in life, including:


  • developing a limp

  • hip pain – especially during the teenage years

  • painful and stiff joints (osteoarthritis)


It does not cause delayed walking, although a child’s gait (the physical action of their walking), may appear waddling as they are unable to move the affected hip through its normal range of movements.


With early diagnosis and treatment, most children are able to develop normally and have a full range of movement in their hip.


Diagnosing DDH

Your baby's hips should be checked as part of the newborn physical examination within 72 hours of being born. The examination involves gently moving your baby's hip joints to check if there are any problems. It should not cause them any discomfort. Your baby should have an ultrasound scan of their hip before they're 2-6 weeks old if a doctor, midwife or nurse thinks their hip feels unstable.


Babies should also have an ultrasound scan of their hip before they're 6 weeks old if:

  • there have been childhood hip problems in your family (parents, brothers or sisters)

  • your baby was in the breech position (feet or bottom downwards) in the last month of pregnancy

  • your baby was born in the breech position

  • If you have had twins or multiples and one of the babies has any of these risk factors, each baby should have an ultrasound scan of their hips by the time they're 6 weeks old

Often a baby's hip stabilises on its own before the scan is due, but they should still be checked to make sure.


Clicky hips – as opposed to clunky hips- which is the sensation the examiner feels when carrying out the hip tests, and which parents often feel when changing nappies are very frequent, and are usually of no significance, but it is often better to get the hips scanned at around 6 weeks just to be sure. Unequal skin folds at the lower part of the buttock or thigh are not indicators of DDH, although are a common cause of referral!


Ultrasound - Ultrasound screening of all newborn infants occurs in many countries and does pick up more cases, up to twice as many as in areas where there is no ultrasound screening. However, many of the hips with mild DDH detected at screening may never have needed treating as the condition, if mild, can self-correct. For this reason, and the fact that it has not been proven to be cost-effective it is not part of the UK national screening programme.


Treating DDH

All babies with a DDH, whether confirmed or suspected should be referred for further assessment to a Paediatric Orthopaedic (Bone and Joint) Specialist. Babies diagnosed with DDH early in life are usually treated with a fabric hip splint often called a Pavlik harness.

This secures both of your baby's hips in a stable position and encourages the ball of the hip to sit tightly in the socket and encourages normal hip development. The harness needs to be worn constantly for several weeks and should generally not be removed but don’t worry if this is recommended, you will be given detailed instruction as to how to care for your child whilst using this device such as:

  • how to change your baby's clothes without removing the harness – nappies can be worn normally

  • cleaning the harness if it's soiled – it still should not be removed, but can be cleaned with detergent and an old toothbrush or nail brush

  • positioning your baby while they sleep – they should be placed on their back and not on their side

  • how to avoid skin irritation around the straps of the harness – you may be advised to wrap some soft, hygienic material around the bands

  • eventually, you may be given advice on removing and replacing the harness for short periods of time until it can be permanently removed

You'll be encouraged to allow your baby to move freely when the harness is off. Swimming is often recommended as any movement will encourage normal growth of the hip joint. The harness usually needs to be adjusted as your baby grows and this is usually done at follow-up appointments when your clinician will also discuss your baby's progress.


Surgery

Surgery may sometimes be needed if your baby is diagnosed with DDH after they're 6 months old, or if the Pavlik harness has not helped.


The most common surgery is called reduction. This involves placing the femoral head back into the hip socket.

Reduction surgery is done under general anaesthetic and may be done as either:


  • closed reduction – the femoral head is placed in the hip socket without making any large cuts

  • open reduction – a cut is made in the groin to allow the surgeon to place the femoral head into the hip socket


Your child may need to wear a cast for at least 12 weeks after the operation. Their hip will be checked under general anaesthetic again after 6 weeks, to make sure it's stable and healing well. After this investigation, your child will probably wear a cast for at least another 6 weeks to allow their hip to fully stabilise.


Some children may also require bone surgery (osteotomy) during an open reduction, or at a later date, to help create a deeper ball and socket and to correct any bone deformities.


Get help and support from the charity ‘Steps’ if your baby's been diagnosed with DDH


Late-stage signs of DDH

The newborn physical examination, and the usual check at 6 to 8 weeks, aims to diagnose DDH early, but sometimes hip problems can develop after these checks. It's important to contact a GP as soon as possible if you notice your child has developed any of the following symptoms:


  • restricted movement in 1 leg when you change their nappy

  • one leg dragging behind the other when they crawl

  • one leg appearing longer than the other

  • uneven skin folds in the buttocks or thighs

  • a limp, walking on toes, or developing an abnormal "waddling" walk

Your child should then be referred to an orthopaedic specialist with experience in treating late diagnosed DDH in hospital for an ultrasound scan or an X-ray if your doctor thinks there's a problem with their hip.


Preventing DDH

It's important to remember DDH is genetically determined and cannot be prevented and it is nobody's fault. A baby's hips are naturally more flexible for a short period after birth. But if your baby spends a lot of time tightly wrapped (swaddled) with their legs straight and pressed together, there's a risk this may affect their hip development. Using hip-healthy swaddling techniques can reduce this risk. Make sure your baby is able to move their hips and knees freely to kick.





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